A filter generally consists of a filter tank, a water pump, and filtering materials. The working principle is to pump the water from the fish tank into a filter tank, which is filtered by the filter material inside the tank. The filter material leaves harmful substances or impurities in the water in the filter tank, and the filtered water returns to the fish tank.

According to the direction of water flow, the order of setting the filter materials for the filtration system is: water inlet → (water pump) → physical filtration → chemical filtration → biological filtration → (water pump) → water outlet.

For example, for chestnuts, the filter material setting of the outer filter barrel (according to the direction of water flow):

1. Coarse filter cotton (two layers), wrapped outside the water inlet of the outer filter barrel, for easier cleaning and replacement. 2. Biochemical cotton, in the case of poor filtration in the previous stage, adsorbs organic matter to achieve filtration. 3. The volume of glass ring shall account for 3~5% of the total tank water volume, and Nitrifying bacteria shall be cultivated. 4. Coarse filter cotton (one layer) is mainly used to disperse and adsorb metabolic waste from bacteria.

Other types of filtering equipment can be set according to the above external filter barrels, and other filter materials can be placed according to the actual situation.

The required volume of filter material for the filtration system - glass ring: accounts for 3-5% of the total cylinder water volume; Filter (aquarium)#Materials suitable for aquarium filtration: accounting for 5-10% of the total cylinder water volume; Biosphere: accounts for more than 10% of the total water volume in the tank (generally only applicable to tidal and dry (trickle) filtration).

Attention: The filtration system must be continuously on for 24 hours.

1. Upper circulating filtration (upper filtration)

It is placed on the upper part of the fish tank, and the water is pumped into the upper filter tank through a Submersible pump. The water flows back to the fish tank through the bottom outlet pipe after passing through the filter cotton, biochemical cotton and various filter materials.

Low price, simple structure, easy cleaning and maintenance, but it takes up space and affects aesthetics, making it unsuitable for straw tanks.

2. Trickle filtration

Simply put, it refers to the advanced version of upper filtration. The upper layer of the filtration tank is a physical filtration chamber, where filter cotton and biochemical cotton are placed. The lower layers are respectively filled with filter materials such as biochemical balls, rattan cotton, glass rings, quartz balls, and bacterial houses.

The filtering effect is good, occupying space, affecting aesthetics, and the water flow is large, making it suitable for fish tanks with covers.

3. Back filter and side filter

The interior is divided into several small compartments for placing filter materials and circulation pumps, with an overflow port on one side. When the water pump draws water from the filtering section to the fish tank, the water overflowing from the fish tank flows into the first compartment of the filtering section through the overflow port, and under the guidance of the partition, flows through various filter materials. The water passes through the water pump from the last compartment and is then fed back into the fish tank to form a circulation.

4. Bottom cylinder filtration

Utilize a large filter tank (called a bottom tank) placed in the bottom cabinet, connect it to the main cylinder through a pipeline, and use a water pump to complete water circulation. The filter tank is equipped with different filter materials or equipment according to its size and actual needs. Bottom cylinder filtration generally adopts overflow drainage methods, which are divided into various forms such as triangular overflow, square overflow, circular overflow, triple overflow pipe overflow, and non perforated overflow.

Beautiful and well filtered, but with a complex structure, high production costs, and increased power consumption.

5. External filter barrel filtration

There are several layers in the bucket, and each layer can be placed with different filter materials. The water in the Aquarium can continuously flow through each layer of filter materials in the bucket by using the pump inside or outside the bucket, so as to achieve the purpose of circulating filtration. Before starting, it is necessary to ensure that the bucket and inlet and outlet pipes are full of water to avoid air accumulation.

Low noise, good biochemical filtration effect, but weak physical filtration effect, and cumbersome cleaning and start-up.

6. External filter barrel filtration

The external filter is a semi closed filter hung on the cylinder wall. Different filter material placement areas are set inside. The water in the aquarium tank is sucked into the filter by the water pump attached to the body and flows through various filter materials to achieve the purpose of circulating filtration

Low price, easy to use, not suitable for large fish tanks and grass tanks.

7. Built-in filtration (submerged filter)

The pump is connected to the filter box and placed in water for use. Various filter materials (usually biochemical cotton, which can be matched with various filter materials) are placed inside the filter box for bacterial cultivation.

Silent, easy to use, suitable for straw vats.

8. Biochemical cotton filtration/pneumatic biochemical filter.

The aeration pump is used to blow air into the next biochemical cotton to make the water flow from the outside of the cotton to the inside of the cotton. At the same time, the continuous blowing of the air pump provides a large amount of oxygen for Nitrifying bacteria. During the flow, the dirt is left on the biochemical cotton, which is then decomposed by the water or nitrobacteria on the cotton to form a biological filtration environment.

Suitable for small fish tanks and small fish, not suitable for aquatic plants and large fish tanks.

A reverse air lift filter is a device that reverses the direction of water flow and can solve the problem of dissolved oxygen in water, providing sufficient oxygen supply for beneficial bacteria (aerobic bacteria).

9. Gas lift and anti gas lift filtration gas lift:

The working principle is similar to that of water goblin. The gas stone at the bottom of the container vents, and the bubbles rise to drive the water flow, providing water containing oxygen and nutrients needed for the survival of Nitrifying bacteria in the filter material, thus playing the role of biological filtration.

Anti air lift: The internal structure is basically the same as that of air lift, with the bottom water inlet becoming the outlet. Reverse air lift is generally placed below the outlet of the upper filter to receive the falling water from the upper filter.

Advantages: concise, efficient, convenient to use, economical, and many people DIY.